/*
** $Id: lua.c,v 1.230 2017/01/12 17:14:26 roberto Exp $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/

#define lua_c

#include "lprefix.h"


#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"



#if !defined(LUA_PROMPT)
#define LUA_PROMPT      "> "
#define LUA_PROMPT2     ">> "
#endif

#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME        "lua"
#endif

#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT        512
#endif

#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR        "LUA_INIT"
#endif

#define LUA_INITVARVERSION  LUA_INIT_VAR LUA_VERSUFFIX


/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if !defined(lua_stdin_is_tty)  /* { */

#if defined(LUA_USE_POSIX)  /* { */

#include <unistd.h>
#define lua_stdin_is_tty()  isatty(0)

#elif defined(LUA_USE_WINDOWS)  /* }{ */

#include <io.h>
#include <windows.h>

#define lua_stdin_is_tty()  _isatty(_fileno(stdin))

#else               /* }{ */

/* ISO C definition */
#define lua_stdin_is_tty()  1  /* assume stdin is a tty */

#endif              /* } */

#endif              /* } */


/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if !defined(lua_readline)  /* { */

#if defined(LUA_USE_READLINE)   /* { */

#include <readline/readline.h>
#include <readline/history.h>
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,line)    ((void)L, add_history(line))
#define lua_freeline(L,b)   ((void)L, free(b))

#else               /* }{ */

#define lua_readline(L,b,p) \
        ((void)L, fputs(p, stdout), fflush(stdout),  /* show prompt */ \
        fgets(b, LUA_MAXINPUT, stdin) != NULL)  /* get line */
#define lua_saveline(L,line)    { (void)L; (void)line; }
#define lua_freeline(L,b)   { (void)L; (void)b; }

#endif              /* } */

#endif              /* } */




static lua_State* globalL = NULL;

static const char* progname = LUA_PROGNAME;


/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop( lua_State* L, lua_Debug* ar ) {
    ( void )ar; /* unused arg. */
    lua_sethook( L, NULL, 0, 0 ); /* reset hook */
    luaL_error( L, "interrupted!" );
}


/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction( int i ) {
    signal( i, SIG_DFL ); /* if another SIGINT happens, terminate process */
    lua_sethook( globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1 );
}


static void print_usage( const char* badoption ) {
    lua_writestringerror( "%s: ", progname );

    if ( badoption[1] == 'e' || badoption[1] == 'l' ) {
        lua_writestringerror( "'%s' needs argument\n", badoption );
    }
    else {
        lua_writestringerror( "unrecognized option '%s'\n", badoption );
    }

    lua_writestringerror(
        "usage: %s [options] [script [args]]\n"
        "Available options are:\n"
        "  -e stat  execute string 'stat'\n"
        "  -i       enter interactive mode after executing 'script'\n"
        "  -l name  require library 'name'\n"
        "  -v       show version information\n"
        "  -E       ignore environment variables\n"
        "  --       stop handling options\n"
        "  -        stop handling options and execute stdin\n"
        ,
        progname );
}


/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message( const char* pname, const char* msg ) {
    if ( pname ) {
        lua_writestringerror( "%s: ", pname );
    }

    lua_writestringerror( "%s\n", msg );
}


/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report( lua_State* L, int status ) {
    if ( status != LUA_OK ) {
        const char* msg = lua_tostring( L, -1 );
        l_message( progname, msg );
        lua_pop( L, 1 ); /* remove message */
    }

    return status;
}


/*
** Message handler used to run all chunks
*/
static int msghandler( lua_State* L ) {
    const char* msg = lua_tostring( L, 1 );

    if ( msg == NULL ) { /* is error object not a string? */
        if ( luaL_callmeta( L, 1, "__tostring" ) && /* does it have a metamethod */
                lua_type( L, -1 ) == LUA_TSTRING ) { /* that produces a string? */
            return 1;    /* that is the message */
        }
        else
            msg = lua_pushfstring( L, "(error object is a %s value)",
                                   luaL_typename( L, 1 ) );
    }

    luaL_traceback( L, L, msg, 1 ); /* append a standard traceback */
    return 1;  /* return the traceback */
}


/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall( lua_State* L, int narg, int nres ) {
    int status;
    int base = lua_gettop( L ) - narg; /* function index */
    lua_pushcfunction( L, msghandler ); /* push message handler */
    lua_insert( L, base ); /* put it under function and args */
    globalL = L;  /* to be available to 'laction' */
    signal( SIGINT, laction ); /* set C-signal handler */
    status = lua_pcall( L, narg, nres, base );
    signal( SIGINT, SIG_DFL ); /* reset C-signal handler */
    lua_remove( L, base ); /* remove message handler from the stack */
    return status;
}


static void print_version( void ) {
    lua_writestring( LUA_COPYRIGHT, strlen( LUA_COPYRIGHT ) );
    lua_writeline();
}


/*
** Create the 'arg' table, which stores all arguments from the
** command line ('argv'). It should be aligned so that, at index 0,
** it has 'argv[script]', which is the script name. The arguments
** to the script (everything after 'script') go to positive indices;
** other arguments (before the script name) go to negative indices.
** If there is no script name, assume interpreter's name as base.
*/
static void createargtable( lua_State* L, char** argv, int argc, int script ) {
    int i, narg;

    if ( script == argc ) {
        script = 0;    /* no script name? */
    }

    narg = argc - ( script + 1 ); /* number of positive indices */
    lua_createtable( L, narg, script + 1 );

    for ( i = 0; i < argc; i++ ) {
        lua_pushstring( L, argv[i] );
        lua_rawseti( L, -2, i - script );
    }

    lua_setglobal( L, "arg" );
}


static int dochunk( lua_State* L, int status ) {
    if ( status == LUA_OK ) {
        status = docall( L, 0, 0 );
    }

    return report( L, status );
}


static int dofile( lua_State* L, const char* name ) {
    return dochunk( L, luaL_loadfile( L, name ) );
}


static int dostring( lua_State* L, const char* s, const char* name ) {
    return dochunk( L, luaL_loadbuffer( L, s, strlen( s ), name ) );
}


/*
** Calls 'require(name)' and stores the result in a global variable
** with the given name.
*/
static int dolibrary( lua_State* L, const char* name ) {
    int status;
    lua_getglobal( L, "require" );
    lua_pushstring( L, name );
    status = docall( L, 1, 1 ); /* call 'require(name)' */

    if ( status == LUA_OK ) {
        lua_setglobal( L, name );    /* global[name] = require return */
    }

    return report( L, status );
}


/*
** Returns the string to be used as a prompt by the interpreter.
*/
static const char* get_prompt( lua_State* L, int firstline ) {
    const char* p;
    lua_getglobal( L, firstline ? "_PROMPT" : "_PROMPT2" );
    p = lua_tostring( L, -1 );

    if ( p == NULL ) {
        p = ( firstline ? LUA_PROMPT : LUA_PROMPT2 );
    }

    return p;
}

/* mark in error messages for incomplete statements */
#define EOFMARK     "<eof>"
#define marklen     (sizeof(EOFMARK)/sizeof(char) - 1)


/*
** Check whether 'status' signals a syntax error and the error
** message at the top of the stack ends with the above mark for
** incomplete statements.
*/
static int incomplete( lua_State* L, int status ) {
    if ( status == LUA_ERRSYNTAX ) {
        size_t lmsg;
        const char* msg = lua_tolstring( L, -1, &lmsg );

        if ( lmsg >= marklen && strcmp( msg + lmsg - marklen, EOFMARK ) == 0 ) {
            lua_pop( L, 1 );
            return 1;
        }
    }

    return 0;  /* else... */
}


/*
** Prompt the user, read a line, and push it into the Lua stack.
*/
static int pushline( lua_State* L, int firstline ) {
    char buffer[LUA_MAXINPUT];
    char* b = buffer;
    size_t l;
    const char* prmt = get_prompt( L, firstline );
    int readstatus = lua_readline( L, b, prmt );

    if ( readstatus == 0 ) {
        return 0;    /* no input (prompt will be popped by caller) */
    }

    lua_pop( L, 1 ); /* remove prompt */
    l = strlen( b );

    if ( l > 0 && b[l - 1] == '\n' ) { /* line ends with newline? */
        b[--l] = '\0';    /* remove it */
    }

    if ( firstline && b[0] == '=' ) { /* for compatibility with 5.2, ... */
        lua_pushfstring( L, "return %s", b + 1 );    /* change '=' to 'return' */
    }
    else {
        lua_pushlstring( L, b, l );
    }

    lua_freeline( L, b );
    return 1;
}


/*
** Try to compile line on the stack as 'return <line>;'; on return, stack
** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn( lua_State* L ) {
    const char* line = lua_tostring( L, -1 ); /* original line */
    const char* retline = lua_pushfstring( L, "return %s;", line );
    int status = luaL_loadbuffer( L, retline, strlen( retline ), "=stdin" );

    if ( status == LUA_OK ) {
        lua_remove( L, -2 ); /* remove modified line */

        if ( line[0] != '\0' ) { /* non empty? */
            lua_saveline( L, line );    /* keep history */
        }
    }
    else {
        lua_pop( L, 2 );    /* pop result from 'luaL_loadbuffer' and modified line */
    }

    return status;
}


/*
** Read multiple lines until a complete Lua statement
*/
static int multiline( lua_State* L ) {
    for ( ;; ) { /* repeat until gets a complete statement */
        size_t len;
        const char* line = lua_tolstring( L, 1, &len ); /* get what it has */
        int status = luaL_loadbuffer( L, line, len, "=stdin" ); /* try it */

        if ( !incomplete( L, status ) || !pushline( L, 0 ) ) {
            lua_saveline( L, line ); /* keep history */
            return status;  /* cannot or should not try to add continuation line */
        }

        lua_pushliteral( L, "\n" ); /* add newline... */
        lua_insert( L, -2 ); /* ...between the two lines */
        lua_concat( L, 3 ); /* join them */
    }
}


/*
** Read a line and try to load (compile) it first as an expression (by
** adding "return " in front of it) and second as a statement. Return
** the final status of load/call with the resulting function (if any)
** in the top of the stack.
*/
static int loadline( lua_State* L ) {
    int status;
    lua_settop( L, 0 );

    if ( !pushline( L, 1 ) ) {
        return -1;    /* no input */
    }

    if ( ( status = addreturn( L ) ) != LUA_OK ) { /* 'return ...' did not work? */
        status = multiline( L );    /* try as command, maybe with continuation lines */
    }

    lua_remove( L, 1 ); /* remove line from the stack */
    lua_assert( lua_gettop( L ) == 1 );
    return status;
}


/*
** Prints (calling the Lua 'print' function) any values on the stack
*/
static void l_print( lua_State* L ) {
    int n = lua_gettop( L );

    if ( n > 0 ) { /* any result to be printed? */
        luaL_checkstack( L, LUA_MINSTACK, "too many results to print" );
        lua_getglobal( L, "print" );
        lua_insert( L, 1 );

        if ( lua_pcall( L, n, 0, 0 ) != LUA_OK )
            l_message( progname, lua_pushfstring( L, "error calling 'print' (%s)",
                                                  lua_tostring( L, -1 ) ) );
    }
}


/*
** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
** print any results.
*/
static void doREPL( lua_State* L ) {
    int status;
    const char* oldprogname = progname;
    progname = NULL;  /* no 'progname' on errors in interactive mode */

    while ( ( status = loadline( L ) ) != -1 ) {
        if ( status == LUA_OK ) {
            status = docall( L, 0, LUA_MULTRET );
        }

        if ( status == LUA_OK ) {
            l_print( L );
        }
        else {
            report( L, status );
        }
    }

    lua_settop( L, 0 ); /* clear stack */
    lua_writeline();
    progname = oldprogname;
}


/*
** Push on the stack the contents of table 'arg' from 1 to #arg
*/
static int pushargs( lua_State* L ) {
    int i, n;

    if ( lua_getglobal( L, "arg" ) != LUA_TTABLE ) {
        luaL_error( L, "'arg' is not a table" );
    }

    n = ( int )luaL_len( L, -1 );
    luaL_checkstack( L, n + 3, "too many arguments to script" );

    for ( i = 1; i <= n; i++ ) {
        lua_rawgeti( L, -i, i );
    }

    lua_remove( L, -i ); /* remove table from the stack */
    return n;
}


static int handle_script( lua_State* L, char** argv ) {
    int status;
    const char* fname = argv[0];

    if ( strcmp( fname, "-" ) == 0 && strcmp( argv[-1], "--" ) != 0 ) {
        fname = NULL;    /* stdin */
    }

    status = luaL_loadfile( L, fname );

    if ( status == LUA_OK ) {
        int n = pushargs( L ); /* push arguments to script */
        status = docall( L, n, LUA_MULTRET );
    }

    return report( L, status );
}



/* bits of various argument indicators in 'args' */
#define has_error   1   /* bad option */
#define has_i       2   /* -i */
#define has_v       4   /* -v */
#define has_e       8   /* -e */
#define has_E       16  /* -E */

/*
** Traverses all arguments from 'argv', returning a mask with those
** needed before running any Lua code (or an error code if it finds
** any invalid argument). 'first' returns the first not-handled argument
** (either the script name or a bad argument in case of error).
*/
static int collectargs( char** argv, int* first ) {
    int args = 0;
    int i;

    for ( i = 1; argv[i] != NULL; i++ ) {
        *first = i;

        if ( argv[i][0] != '-' ) { /* not an option? */
            return args;    /* stop handling options */
        }

        switch ( argv[i][1] ) { /* else check option */
        case '-':  /* '--' */
            if ( argv[i][2] != '\0' ) { /* extra characters after '--'? */
                return has_error;    /* invalid option */
            }

            *first = i + 1;
            return args;

        case '\0':  /* '-' */
            return args;  /* script "name" is '-' */

        case 'E':
            if ( argv[i][2] != '\0' ) { /* extra characters after 1st? */
                return has_error;    /* invalid option */
            }

            args |= has_E;
            break;

        case 'i':
            args |= has_i;  /* (-i implies -v) *//* FALLTHROUGH */

        case 'v':
            if ( argv[i][2] != '\0' ) { /* extra characters after 1st? */
                return has_error;    /* invalid option */
            }

            args |= has_v;
            break;

        case 'e':
            args |= has_e;  /* FALLTHROUGH */

        case 'l':  /* both options need an argument */
            if ( argv[i][2] == '\0' ) { /* no concatenated argument? */
                i++;  /* try next 'argv' */

                if ( argv[i] == NULL || argv[i][0] == '-' ) {
                    return has_error;    /* no next argument or it is another option */
                }
            }

            break;

        default:  /* invalid option */
            return has_error;
        }
    }

    *first = i;  /* no script name */
    return args;
}


/*
** Processes options 'e' and 'l', which involve running Lua code.
** Returns 0 if some code raises an error.
*/
static int runargs( lua_State* L, char** argv, int n ) {
    int i;

    for ( i = 1; i < n; i++ ) {
        int option = argv[i][1];
        lua_assert( argv[i][0] == '-' ); /* already checked */

        if ( option == 'e' || option == 'l' ) {
            int status;
            const char* extra = argv[i] + 2;  /* both options need an argument */

            if ( *extra == '\0' ) {
                extra = argv[++i];
            }

            lua_assert( extra != NULL );
            status = ( option == 'e' )
                     ? dostring( L, extra, "=(command line)" )
                     : dolibrary( L, extra );

            if ( status != LUA_OK ) {
                return 0;
            }
        }
    }

    return 1;
}



static int handle_luainit( lua_State* L ) {
    const char* name = "=" LUA_INITVARVERSION;
    const char* init = getenv( name + 1 );

    if ( init == NULL ) {
        name = "=" LUA_INIT_VAR;
        init = getenv( name + 1 ); /* try alternative name */
    }

    if ( init == NULL ) {
        return LUA_OK;
    }
    else if ( init[0] == '@' ) {
        return dofile( L, init + 1 );
    }
    else {
        return dostring( L, init, name );
    }
}


/*
** Main body of stand-alone interpreter (to be called in protected mode).
** Reads the options and handles them all.
*/
static int pmain( lua_State* L ) {
    int argc = ( int )lua_tointeger( L, 1 );
    char** argv = ( char** )lua_touserdata( L, 2 );
    int script;
    int args = collectargs( argv, &script );
    luaL_checkversion( L ); /* check that interpreter has correct version */

    if ( argv[0] && argv[0][0] ) {
        progname = argv[0];
    }

    if ( args == has_error ) { /* bad arg? */
        print_usage( argv[script] ); /* 'script' has index of bad arg. */
        return 0;
    }

    if ( args & has_v ) { /* option '-v'? */
        print_version();
    }

    if ( args & has_E ) { /* option '-E'? */
        lua_pushboolean( L, 1 ); /* signal for libraries to ignore env. vars. */
        lua_setfield( L, LUA_REGISTRYINDEX, "LUA_NOENV" );
    }

    luaL_openlibs( L ); /* open standard libraries */
    createargtable( L, argv, argc, script ); /* create table 'arg' */

    if ( !( args & has_E ) ) { /* no option '-E'? */
        if ( handle_luainit( L ) != LUA_OK ) { /* run LUA_INIT */
            return 0;    /* error running LUA_INIT */
        }
    }

    if ( !runargs( L, argv, script ) ) { /* execute arguments -e and -l */
        return 0;    /* something failed */
    }

    if ( script < argc && /* execute main script (if there is one) */
            handle_script( L, argv + script ) != LUA_OK ) {
        return 0;
    }

    if ( args & has_i ) { /* -i option? */
        doREPL( L );    /* do read-eval-print loop */
    }
    else if ( script == argc &&
              !( args & ( has_e | has_v ) ) ) { /* no arguments? */
        if ( lua_stdin_is_tty() ) { /* running in interactive mode? */
            print_version();
            doREPL( L ); /* do read-eval-print loop */
        }
        else {
            dofile( L, NULL );    /* executes stdin as a file */
        }
    }

    lua_pushboolean( L, 1 ); /* signal no errors */
    return 1;
}


int main( int argc, char** argv ) {
    int status, result;
    lua_State* L = luaL_newstate();  /* create state */

    if ( L == NULL ) {
        l_message( argv[0], "cannot create state: not enough memory" );
        return EXIT_FAILURE;
    }

    lua_pushcfunction( L, &pmain ); /* to call 'pmain' in protected mode */
    lua_pushinteger( L, argc ); /* 1st argument */
    lua_pushlightuserdata( L, argv ); /* 2nd argument */
    status = lua_pcall( L, 2, 1, 0 ); /* do the call */
    result = lua_toboolean( L, -1 ); /* get result */
    report( L, status );
    lua_close( L );
    return ( result && status == LUA_OK ) ? EXIT_SUCCESS : EXIT_FAILURE;
}

